There are two kinds:
Use the Ellipse tool in the line tool.
This is a path to draw. Hold down the SHIFT key and pull the positive circle out.
Click "Path" and click "Draw path with foreground color" below the point.
Delete the work path.
The circular line of this drawing is only 1 pixels wide. If you want to widen, use "stroke" to do it. Suitable for thin line circular images.
Another is to use the "marquee tool" in the "elliptical marquee tool" to do. Pull out the horizontal and vertical two guides first. Click "View" and tick "align".
With the elliptical marquee tool, hold down the SHIFT key, pull out the positive circle Marquee, fill the foreground color, and deselect the selection.
Move to the cross-center position of the two guides with the Move tool. Then use the Ellipse Marquee tool to pull another round marquee that is smaller than the first one.
Use the Move tool to pull it onto the first circular pattern and adjust the position to concentric with the first circle.
With the transform selection tool in the selection tool, hold down the SHIFT key, pull the corners, and adjust the size of the circular selection to determine the width of the circular pattern line. Adjust concentricity at any time.
When you are satisfied, use the Edit \ Clear tool to clear the color of the Circle Marquee and cancel the selection. A circular shape that can be arbitrarily defined in width is completed.
How to draw a circle in PS